package com.xk._03真题骗._05动态规划;

/*
 * @description: https://leetcode.cn/problems/li-wu-de-zui-da-jie-zhi-lcof/
 * @author: xu
 * @date: 2022/11/3 10:52
 */
public class _面试题47礼物的最大价值 {
    public int maxValue1(int[][] grid) {
        int row = grid.length;
        int col = grid[0].length;
        int[][] dp = new int[row][col];
        dp[0][0] = grid[0][0];
        for (int i = 1; i < row; i++) { // 第0列
            dp[i][0] = dp[i-1][0] + grid[i][0];
        }
        for (int i = 1; i < col; i++) { // 第0行
            dp[0][i] = dp[0][i-1] + grid[0][i];
        }
        for (int i = 1; i < row; i++) {
            for (int j = 1; j < col; j++) {
                int max = Math.max(dp[i-1][j], dp[i][j-1]);
                dp[i][j] = max + grid[i][j];
            }
        }
        return dp[row-1][col-1];
    }

    // 二维数组--动态规划
    public int maxValue2(int[][] grid) {
        int rows = grid.length;
        int cols = grid[0].length;
        int[][] dp = new int[rows + 1][cols + 1];
        for (int i = 1; i <= rows; i++) {
            for (int j = 1; j <= cols; j++) {
                int max = Math.max(dp[i-1][j], dp[i][j-1]);
                dp[i][j] = max + grid[i-1][j-1];
            }
        }
        return dp[rows][cols];
    }

    // 一维数组优化
    public int maxValue(int[][] grid) {
        int rows = grid.length;
        int cols = grid[0].length;
        int[] dp = new int[cols + 1];
        for (int i = 1; i <= rows; i++) {
            for (int j = 1; j <= cols; j++) {
                int max = Math.max(dp[j], dp[j-1]);
                dp[j] = max + grid[i-1][j-1];
            }
        }
        return dp[cols];
    }
}
